similar to: octonions

Hi I have written a whole bunch of methods for objects of class "octonion". [ an octonion is a single column of an eight-row matrix. Octonions have their own multiplication rules and are a generalization of quaternions, which are columns of a four-row matrix. ] So far I've done about a dozen generic functions such as seq.octonion(), rep.octonion(), [<-.octonion(), and so on

Hi it says in R-exts that A method must have all the arguments of the generic, including ... if the generic does. A method must have arguments in exactly the same order as the generic. A method should use the same defaults as the generic. So, how come the arguments for rep() are (x, times, ...) and the arguments for rep.default() are (x, times, length.out, each, ...) ?

Hi How do I test for an object having a particular virtual class? In the following, "onion" is a virtual class, and "octonion" is a non-virtual class contained in onion. The last call to inherits() gives FALSE [R-2.5.0], when inherits.Rd led me to expect TRUE. setClass("onion", representation = "VIRTUAL" )

Hi section 6.1 of R-exts suggests that a package can take over a function in the base package and make it generic. I want to do this with Re() and have the following lines in my R code: "Re" <- function(x){UseMethod("Re" )} "Re.default" <- get("Re" ,pos=NULL,mode="function") "Re.octonion" <- function(x){give.comp(x,1)}

In the Green Book, section 7.5 discusses new vector classes and uses quaternions as an example of a vector class that needs more than one number per element. I would like to define a new class that has a numeric vector and a logical vector of the same length that specifies whether the measurement was accurate. The following code does not behave as desired: >

Dear List I have just uploaded a new package, "onion", to CRAN. It provides some functionality for manipulating and visualizing quaternions and octonions. All comments welcome! enjoy rksh -- Robin Hankin Uncertainty Analyst National Oceanography Centre, Southampton European Way, Southampton SO14 3ZH, UK tel 023-8059-7743 _______________________________________________

Hi In NEWS, it says R CMD check now tests that the package can be loaded, and that the package and namespace (if there is one) can each be loaded in startup code (before the standard packages are loaded). For package "onion", I think I have followed all of sections 1.6.1 - 1.6.6 of R-exts, and it passes R CMD check for R-2.3.1. However, using R version 2.4.0 Under

Hi has anyone coded up domain colouring for visualizing complex analytic functions (such as elliptic functions)? [ the idea is to depict a complex function f(z) using a filled.contour() variant in which the hue is given by Arg(f(z)), and the saturation by Mod(f(z)). ] -- Robin Hankin Uncertainty Analyst Southampton Oceanography Centre European Way, Southampton SO14 3ZH, UK tel

Hi. I have a factor and I want to extract just those elements that appear exactly once. How to do this? Toy example follows. > a <- as.factor(c(rep("oak",5) ,rep("ash",1),rep("elm",1),rep ("beech",4))) > a [1] oak oak oak oak oak ash elm beech beech beech beech Levels: ash beech elm oak > table(a) a ash beech elm oak

Hi If string <- "xyz" f <- function(x){1 + sin(cos(x)) + exp(x^2)} How do I manipulate "string" and f() to give the string "1 + sin(cos(xyz)) + exp(xyz^2)" ? -- Robin Hankin Uncertainty Analyst National Oceanography Centre, Southampton European Way, Southampton SO14 3ZH, UK tel 023-8059-7743

Hi In Sweave, how does one change the size of the plots? I tried using a hook: <<echo=FALSE, print=FALSE, fig=TRUE>>= options(SweaveHooks=list(fig=function() ps.options(width=1))) library(graphics) pairs(iris) @ but this didn't change the size of the figure. How to make the figures a different size? -- Robin Hankin Uncertainty Analyst National Oceanography Centre,

Hi. Is there a straightforward way to convert a character string containing comma-delimited numbers to a numeric vector? In my application, I use system(executable.string, intern=TRUE) which returns a string like "[0.E-38, 2.096751179214927596171268230, 3.678944959657480671183123052, 4.976528845643001020345216157, 6.072390165503099343887569007, 7.007958550337542210168866070,

Hi ?lines says For 'type = "h"', 'col' can be a vector and will be recycled as needed. Why doesn't lines() recycle colours for other types? If I type > plot(0:1,0:1,type="n") > lines(runif(11),runif(11),col=c("red","green")) > then all ten lines are red, with no warning given. Is there a reason why

Hi I'm developing an R package that needs to execute some code written in pari/gp. I've used this before from an R package (elliptic) but the interface is very basic: the R function creates a string such as the following: string <- echo ' ellwp ([ 2+0*I , 0+2*I ], 1+0*I )' | gp -q And then system(string) returns the output from gp which then needs to be text processed

Hi How do I specify an S4 class with a slot that is potentially numeric, but NA by default? I want the slot to be NA until I calculate its value (an expensive operation, not needed for all applications). When its value is known, I will create a new object with the correct value inserted in the slot. I want "NA" to signify "not known". My attempt fails because

Hi how do I extract those components of a list that satisfy a certain requirement? If jj <- list(list(a=1,b=4:7),list(a=5,b=3:6),list(a=10,b=4:5)) I want just the components of jj that have b[1] ==4 which in this case would be the first and third of jj, viz list (jj[[1]],jj[[3]]). How to do this efficiently? My only idea was to loop through jj, and set unwanted components to NULL,

Hi How do I make do.call() take "+" as a function for a list of more than two elements? Toy problem follows: f <- function(i){matrix((1:6)^i,2,3)} # Thus f() returns a matrix of size 2x3; I want to add a whole bunch of such matrices, # as in f(1) + f(2) + f(3) + f(4) # But: > do.call("+",sapply(1:4,f,simplify=FALSE)) Error in do.call("+",

The following gotcha caught me off-guard just now. I have two matrices, a and b: a <- matrix(1,3,3) b <- matrix(1,1,1) (note that both "a" and "b" are matrices). I want them in a list: > B <- NULL > B[[1]] <- a > B[[2]] <- b > B [[1]] [,1] [,2] [,3] [1,] 1 1 1 [2,] 1 1 1 [3,] 1 1 1 [[2]] [,1] [1,] 1

Hi I have a little vector function that takes a vector A of strictly positive integers and outputs a matrix M each of whose columns is the vector, modified in a complicated combinatorical way. Now I want to generalize the function so that A can include zeroes. Given A, I want to strip out the zeroes, pass it to my function, and pad M with rows at positions corresponding to the zeroes

Hi How do I generate all ways of ordering sets of indistinguishable items? suppose I have two A's, two B's and a C. Then I want AABBC AABCB AACBC ABABC . . .snip... BBAAC . . .snip... CBBAA [there are 5!/(2!*2!) = 30 arrangements. Note AABBC != BBAAC] How do I do this? -- Robin Hankin Uncertainty Analyst National Oceanography Centre, Southampton European Way, Southampton SO14